After having started from Toulon Wednesday, October 13, 2010, the aircraft carrier Charles de Gaulle returned to its base on 15 October. While the ship had envisaged ultimate training off the coast before his deployment towards the Indian ocean, a technical problem was uncovered, after detection of a insulation defect on an electrical cabinet which controls the safety valves for the propulsion…
Investigations to identify the electrical fault highlighted a safety valve malfunction. After expertise, the decision was taken, on Saturday, October 16, of a standard exchange of the valve.

(Jean-Dominique Merchet October 18th, 2010)
The problem concerns the primary circuit of the nuclear boiler.

The defective relief valve on board the aircraft carrier Charles-de-Gaulle – which justified the postponement of his departure on a mission – is located on the primary circuit of the nuclear boiler. However, warns the national navy spokesman, « it is not a nuclear incident », which could put in question the safety of the building and its crew. « In the nuclear domain, all must operate in the nominal way and we found that this was not the case. ».

That has happened? During power outages to overcome the lack of isolation of an electrical cabinet of the propulsion domain – the first issue identified on Thursday – sailors found a micro-leak on one of the three safety valves of the primary circuit. This micro-leak occurred when power was disconnected.
This problem did not call in question directly the nuclear safety because the valve – which did not close correctly, worked in the desired direction, leaving the overpressure escape in an emergency case. …
Except in war time, the national navy must apply the same rules of nuclear safety as a civilian operator, like EDF. It is placed under the control of the defence nuclear safety authority.
This valve replacement is a classic operation without big technical difficulty, said the national navy. It must be however completely stop machines and let cool – what sailors call a “cold stop”. The work will be carried out by specialists of Areva TA (ex-Technicatome) and a spare valve is available. Then will come a testing phase to ‘test’ the new valve, testing it in more extreme conditions than those to which it is usually subject. This technical intervention could last about three weeks.

The aircraft carrier Charles-de-Gaulle still at the stop. Intervention of several weeks is required on the aircraft carrier Charles-de-Gaulle to change a safety valve, announced yesterday the national navy. Departed on a mission Wednesday night, for the first time in two years, Charles de Gaulle was forced to turn back the next day because of an electrical problem and returned to its home the port of Toulon, in the Var.

This time, it is a problem of valve… Back on the “saga” Charles-de-Gaulle.
Departed on Wednesday night for a mission, Charles de Gaulle was forced to turn back the next day because of an electrical problem.

This problem has highlighted a malfunction on a safety valve, that it must therefore change, says the press release.

with AFP | October 17th 2010 at 09h00 • Updating on October 17th 2012 at 16h29

The aircraft carrier Charles de Gaulle at rest for several weeks.

The aircraft carrier Charles de Gaulle is detained “several weeks” to repair the technical incident that had forced the ship to return Wednesday evening its homeport of Toulon.

While he was off the coast of Toulon,…, the nuclear aircraft carrier was forced Wednesday to return to dock to “correct an electrical insulation fault detected on an electrical cabinet of a safety valve control of the propulsion circuit”, recalled the information Service and public relations of the armies (Sirpa).

« This electrical insulation fault has been processed”, he added, but “investigations to identify the electrical fault highlighted a malfunctioning of a safety valve. So “after expertise, decision was taken this Saturday, October 16th for a standard exchange of the valve ».
The Sirpa explained « to achieve this exchange, it was necessary to proceed to a complete stop of the propulsion circuit”, adding that the duration of intervention was “estimated to several weeks ».

Michel Pluviose is Honorary Professor of Le Conservatoire National des Arts et Métiers (CNAM), and formerly Chair of Turbomachines who received his Doctor of Sciences from Université Pierre et Marie Curie - Paris VI. A hands-on engineer, Michel has worked with leading institutions, including as an engineer at Hispano-Suiza, SNECMA, Head of the laboratory at ATTAG (Association technique pour les turbomachines et turbines à gaz), Manager for compressible fluid activities at CETIM (Centre technique des industries mécaniques), and manager of the treaty « Machines hydrauliques et thermiques » at the « Techniques de l’Ingénieur » publications.